TY - JOUR
T1 - Electron irradiation induced transformation of (Pb 5Ca 5)(VO 4) 6F 2 apatite to CaVO 3 perovskite
AU - Dong, Z. L.
AU - White, T. J.
AU - Sun, K.
AU - Wang, L. M.
AU - Ewing, R. C.
PY - 2005/1
Y1 - 2005/1
N2 - Crystallochemical changes of (Pb 5Ca 5)(XV 4) 6F 2 apatite under electron irradiation were examined by transmission electron microscopy. The apatite, a synthetic analog of vanadinite, was moderately stable towards a less intense 300-keV LaB 6 source, while it changed rapidly in structure when exposed to the higher flux of a 200-ke V field emission gun. The electron beam induced transformation of vanadinite proceeds sequentially by (i) migration and loss of fluorine, (ii) lead volatilization and conversion to 2-5-nm platelets of a glaserite-type structure, and (iii) the reduction of V 5+ to V 4+ with the removal of lead and calcium oxide that leads to single-crystal CaVO 3 perovskite as the ultimate product. The phase transformations are interpreted based on the crystallographic relations among the CaVO 3 perovskite, the (Pb 5Ca 5)(VO 4) 6F 2 apatite and the glaserite-type structures, and compositional changes under electron irradiation.
AB - Crystallochemical changes of (Pb 5Ca 5)(XV 4) 6F 2 apatite under electron irradiation were examined by transmission electron microscopy. The apatite, a synthetic analog of vanadinite, was moderately stable towards a less intense 300-keV LaB 6 source, while it changed rapidly in structure when exposed to the higher flux of a 200-ke V field emission gun. The electron beam induced transformation of vanadinite proceeds sequentially by (i) migration and loss of fluorine, (ii) lead volatilization and conversion to 2-5-nm platelets of a glaserite-type structure, and (iii) the reduction of V 5+ to V 4+ with the removal of lead and calcium oxide that leads to single-crystal CaVO 3 perovskite as the ultimate product. The phase transformations are interpreted based on the crystallographic relations among the CaVO 3 perovskite, the (Pb 5Ca 5)(VO 4) 6F 2 apatite and the glaserite-type structures, and compositional changes under electron irradiation.
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U2 - 10.1111/j.1551-2916.2004.00002.x
DO - 10.1111/j.1551-2916.2004.00002.x
M3 - Article
AN - SCOPUS:27544485104
SN - 0002-7820
VL - 88
SP - 184
EP - 190
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
IS - 1
ER -